Coursework Assignment Brief 2025 | NU

Requirements

• Write a report (a text of maximum 2000 words, excluding diagrams, contents, references etc.) to include responses to the tasks from Section 3. You can use technical publications, books or any other usual University Library resources, but you must not make verbatim extracts from these. Sources of information should be acknowledged and appropriately referenced in your report.
• Submit the report via the Blackboard module site no later than 20th Dec 2024.
• Academic Integrity Statement: You must adhere to the University Regulations on academic conduct. Formal inquiry proceedings will be instigated if there is any suspicion of plagiarism or any other form of misconduct in your work. Refer to the University’s Assessment Regulations for Northumbria Awards if you are unclear as to the meaning of these terms. The latest copy is available on the University website.
• Failure to submit: The University requires all students to submit assessed coursework by the deadline stated above. Where the coursework is submitted without prior approval after the published hand-in deadline, penalties will be applied as defined in the University Policy on the Late Submission of Work available at Northumbria University

Specifications

The main objective of the assignment is to propose and evaluate a viable design of a fixed-speed wind energy conversion system (WECS) for remote areas without grid connection. The proposed model should be implemented, and the dynamic performance of the underlying WECS investigated, in Matlab®/Simulink®. The 3-phase WECS should consist of a wound-rotor diesel synchronous generator, a wind turbine induction generator with shunt reactive power compensation, and 3-phase customer loads to be supplied at constant voltage and frequency over the entire wind speed range of [5,12] m/s. The consumer demands are such that 50 kW should be initially delivered to the main load, and then an additional 50 kW to the secondary load, which is subsequently switched on by closing the circuit breaker. You are expected to analyse the system’s transient response to this step load change by computer simulations, making the relevant conclusions/observations from the results obtained.

KD7011 Learning Outcomes

The student will:

• LO1. Evaluate, select, and implement advanced dynamic models, techniques, and procedures for realistic computer simulation studies of WECS performance, considering important practical effects. (AHEP4: M1, M5)
• LO2. Apply knowledge, understanding and computer programming skills to develop a working simulation model for the WECS operation using specialist or conventional software and the manufacturer’s supplied data. (AHEP4: M1, M2)
• LO3. Develop abilities for independent learning and effective time management. (AHEP4: M7, M8)

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KD7011 Tasks

• Design the WECS in the form of a 3-phase line block diagram using, but not limited to, the main structural components given in the Appendix. (15 marks)
• Explain how the voltage and frequency control are achieved at low (say, 5 m/s or 6 m/s) and high (e.g. 11 m/s) wind speeds in the proposed WECS? Identify the corresponding operating modes of the synchronous machine under these two wind conditions. Present details of the voltage and frequency controller configurations for the system operation at higher wind speeds. (15 marks)
• Study the classical d-q theory of 3-phase synchronous and induction generators and present the respective dynamic model equations in a rotor reference frame, defining the meanings of ALL the parameters used. Ignore iron losses and magnetic saturation. (10 marks)
   
• Implement the proposed WECS model in Simulink and run the simulations for 10 s (with a sudden load change occurring at 5.3 s) at a wind speed of 11 m/s. Assume a linear magnetic circuit of the machines, i.e. do not simulate saturation effects. You can use the Wind Turbine block from the Simulink® library, which is based on a 2-D Lookup Table to provide the turbine torque output as a function of the wind and turbine speeds for a typical wind turbine characteristic. Present and discuss qualitatively the generated waveforms for the following performance metrics: voltage [pu]; current [pu] and real power [kW] of the consumer load(s) and induction generator; reactive power of the synchronous machine [kVAr]; induction machine speed [pu], and the line frequency [Hz]. (50 marks)
• The wind turbine generator with the specifications below (ignore the stator losses) is fully loaded operating at 0.92 power factor and 2% absolute slip at rated line frequency. The connection to the electrical network is suddenly lost.

(i) If a wind turbine rotor were brought to a stop by a steel brake disc of a mass of 50 kg, what would be the temperature variation of the brake during the stop? Assume a specific heat for steel of 0.42 kJ/kg °C. (4 marks)

(ii) If the mechanical brake fails to apply, and assuming there are no changes in the aerodynamic forces, how long does it take for the operating speed of the drive train to triple? (6 marks)

Performance Assessment

Task  Technical Objectives

Task 1: WECS design: accuracy (11%) and clarity (4%)

Task 2: Voltage/frequency control at low wind speeds with discussions of the corresponding synchronous machine operating modes: 4%
Voltage/frequency control at high wind speeds with discussions of the respective synchronous machine operating modes: 4%
Configurations of voltage and frequency controllers at higher wind speeds: 2 x 3.5% = 7%

Task 3: Dynamic model equations of synchronous generators in a rotor reference frame: 5% 
Dynamic model equations of induction generators in a rotor reference frame: 5%

Task 4: The following aspects will be considered while assessing the presented results: accuracy, clarity (scaling), labels (units), figure captions, and presentation quality.
Voltage plots: 4%
Current plots (consumer load, induction generator, secondary load): 3 x 4% = 12%
Real power plots (consumer load, induction generator, secondary load): 3 x 4% = 12%
Reactive power of synchronous machine: 4%, Induction machine speed: 4%
System frequency: 4%
Discussions (explanations rather than just observations): 10%

Task 5 :(i)    Calculation of the brake temperature variation: 4%
            (ii)    Calculation of the rotor speed change time: 6%